A light emitting device

Abstract

A light emitting device (1) comprising: an element (2) comprising a bulk low scattering material, the element comprising opposite first and second light incoupling surfaces (21, 22) and a circumferential surface (23) extending between the first and second light incoupling surfaces; at least one red laser diode (3) configured to emit red laser light (31) and arranged at one of the light incoupling surfaces such that the red laser light is coupled into the element through said one of the first and second light incoupling surfaces; a collimator (4) arranged and configured to collimate the red laser light (31); at least one LED (5) configured to emit LED light, the LED being arranged at one of the light incoupling surfaces such that the LED light is coupled into the element through said incoupling surface, and the scattering material being configured to make the path of the laser light visible.

Description

Technical Field

[0001] The present invention relates to a light-emitting device comprising: an element comprising a low-scattering material, the element comprising opposing first and second light-incident surfaces and a circumferential surface extending between and connecting the first and second light-incident surfaces; at least one laser diode; and at least one LED. Background Technology

[0002] Incandescent bulbs are being rapidly replaced by LED-based lighting solutions. Nevertheless, users are recognizing the value of modified lamps that retain the appearance of incandescent bulbs. This can be achieved by simply utilizing the basic structure used to produce glass-based incandescent bulbs and replacing the filament with LEDs that emit white light. One known concept is based on LED filaments placed within such bulbs. The appearance of these lamps is highly appreciated, as they appear highly decorative. Alternatively, filamentary optical fibers can be used to couple LED light into them.

[0003] For example, CN 103016989 A describes a fiber-optic-based incandescent lamp comprising an LED light source, an optical coupling system, and a photoluminescent fiber. The optical coupling system couples light emitted by the light source into the photoluminescent fiber, which in turn converts the light from the light source into a composite light similar to that of an incandescent lamp. The fiber has a diameter in the micrometer range and is flexible, thus mimicking a filament.

[0004] Nevertheless, there is still a desire to make filament lamps more decorative. For example, a flashing appearance is highly desirable. A flame-like effect that simulates the luminous effect of an incandescent lamp filament is also desired.

[0005] In addition, there is a desire to provide a lighting device that also has improved brightness and can be manufactured at a lower cost compared to existing solutions. Summary of the Invention

[0006] The purpose of this invention is to overcome these problems and provide a light-emitting device that, for example, can make filament lamps more decorative by providing a flashing appearance or flame burning effect that simulates the light-emitting effect of an incandescent lamp filament.

[0007] Another object of the present invention is to provide a light-emitting device that also has improved brightness and can be manufactured at a reduced cost, especially compared with existing solutions.

[0008] According to a first aspect of the invention, this and other objectives are achieved by means of a light-emitting device comprising: an element including a volumetric low-scattering material, the element including opposing first and second light-injection surfaces and a circumferential surface extending between and connecting the first and second light-injection surfaces; at least one red laser diode (LD) configured to emit red laser light in operation and disposed at one of the first and second light-injection surfaces such that the red laser light is coupled into the element through said one of the first and second light-injection surfaces; a collimator disposed and configured to collimate the red laser light; at least one LED configured to emit LED light in operation, the at least one LED being disposed at one of the first and second light-injection surfaces such that the LED light is coupled into the element through said one of the first and second light-injection surfaces, and the volumetric low-scattering material of the element being configured to make the path of the laser visible.

[0009] Thus, in particular, by providing a light-emitting device having the following components: a laser diode (LD), a collimator for collimating the laser emitted by the LD, and an element having a low-volume scattering material into which the highly collimated laser is coupled, a light-emitting device is provided that achieves a flame burning effect by means of a decorative spot pattern that mimics the luminous effect of an incandescent lamp filament.

[0010] Furthermore, by combining LD with LED, a light-emitting device is provided that has improved brightness and can be manufactured at a lower cost, especially compared to existing technology solutions.

[0011] In one embodiment, the low-scattering material is a solid material comprising particles smaller than 1 / 10 the wavelength of a red laser.

[0012] Therefore, a light-emitting device is provided in which laser light emitted by an LD is primarily scattered by Rayleigh scattering. This, in turn, provides a light-emitting device with uniform lateral emission.

[0013] In one embodiment, the low-scattering material is a solid material comprising particles larger than the wavelength of a red laser.

[0014] Therefore, a light-emitting device is provided in which the laser emitted by the LD is primarily scattered by Mie scattering. This, in turn, provides a light-emitting device with particularly good control over the direction of light emission.

[0015] In one embodiment, the collimator is configured to provide collimated red laser with an accuracy of less than 1 degree FWHM.

[0016] This ensures increased visibility of the laser emitted by the LD within the element.

[0017] In one embodiment, the element is configured to make the collimated red laser visible over at least a length L in the element, wherein L is at least 5 cm, at least 8 cm, at least 9 cm, or at least 10 cm.

[0018] This ensures that the laser emitted by the LD has particularly good visibility within the element.

[0019] In one embodiment, the low-volume scattering material is a plastic. Suitable plastics include polycarbonate and PMMA.

[0020] Manufacturing costs can be further reduced by using plastic materials. Polycarbonate and PMMA are examples of plastics that are particularly durable and resistant to photodegradation coupled into components.

[0021] In one embodiment, the low-volume scattering material is a foam with light-redirecting properties.

[0022] By using foam with light redirection properties, the weight of the light-emitting device is reduced, while still providing a robust and cost-effective light-emitting device.

[0023] In one embodiment, the light-emitting device further includes at least one reflector disposed at the light-inlet surface of the element, which is opposite to the light-inlet surface of the element on which a red laser diode is disposed, so as to reflect the red laser emitted by the red laser diode back into the element.

[0024] The red laser emitted by the red laser diode can be reflected back into the element in a direction toward the red laser diode or in a direction different from the direction toward the red laser diode. This provides a light-emitting device that can generate various light patterns, offering a more versatile light-emitting device. Furthermore, the reflector improves the visibility of the laser in low-scattering material elements. This improves the effect obtained by the laser. If the red laser emitted by the red laser diode can be reflected back into the element in a direction toward the red laser diode, the visibility of the red laser is further increased by amplification.

[0025] In one embodiment, at least one reflector and a red laser diode are positioned relative to each other in such a way that the red laser reflected by the at least one reflector propagates in a direction different from the direction of propagation of the red laser incident on the at least one reflector. For example, the red laser may be reflected by the at least one reflector at a reflection angle ranging from 10 degrees to 60 degrees.

[0026] Therefore, a light-emitting device is provided that makes more than one laser path visible through a low-volume scattering material, thus enabling the mimicry of more than one filament. This, in turn, allows for the generation of even more different light patterns, providing a light-emitting device with even more functions, requiring minimal additional components.

[0027] In one embodiment, the light-emitting device further includes at least one reflector disposed at the same light-injection surface as the red laser diode and offset from the red laser diode.

[0028] Therefore, a light-emitting device is provided that makes several paths of laser light passing through a low-scattering material visible. This, in turn, allows for the generation of even more different light patterns, providing a particularly versatile light-emitting device that requires minimal additional components.

[0029] In one embodiment, an element comprising a low-scattering material includes at least one segment suitable for not scattering light.

[0030] The provision of a non-scattering section of the element enables the creation of a light-emitting device that makes more than one laser path visible through a low-scattering material. This, in turn, allows for the generation of even more diverse light patterns, providing a more versatile light-emitting device without the need for additional components.

[0031] In one embodiment, an element comprising a low-volume scattering material includes at least one segment covered by a cap or coating.

[0032] By covering at least one segment of the element, a light-emitting device is provided that makes more than one laser path visible through a low-volume scattering material. This, in turn, allows for the generation of even more different light patterns, providing a more versatile light-emitting device that requires minimal additional components.

[0033] In one embodiment, the element comprising a low-scattering material is a light guide, wherein LED light emitted by multiple LEDs can be reflected multiple times by total internal reflection, and the light guide comprises a low-scattering material. The light guide may be rod-shaped.

[0034] Therefore, a light-emitting device is provided, which can achieve a spiral light effect in a very simple structural manner.

[0035] In one embodiment, at least one LED is configured to emit white LED light during operation.

[0036] By combining an LD with a white LED, a light-emitting device is provided that has improved brightness and is particularly simple and therefore can be manufactured at a particularly low cost.

[0037] In one embodiment, the light-emitting device includes a plurality of LEDs configured to emit blue and yellow LED light during operation.

[0038] By combining an LD with blue and yellow LEDs, a color-variable LED is provided. This results in a light-emitting device with improved brightness, which can be manufactured at a lower cost compared to existing technology solutions.

[0039] In one embodiment, the light-emitting device includes a plurality of LEDs configured to emit red, green, and blue LED light during operation.

[0040] By combining LD with RGB LED packaging, a light-emitting device is provided that not only has improved brightness, but can also be manufactured at a lower cost compared to existing technology solutions, and provides full-spectrum control.

[0041] In one embodiment, the light-emitting device further includes a light-transmitting envelope that at least partially surrounds a low-volume scattering material.

[0042] This provides a more robust and durable light-emitting device.

[0043] In one embodiment, the element comprising the low-scattering material is a rod-shaped element.

[0044] This provides a light-emitting device with a particularly simple structure, which in turn makes it particularly inexpensive to manufacture.

[0045] In one embodiment, the element comprising a low-volume scattering material is a filamentary element.

[0046] This provides a light-emitting device that not only comprises a particularly simple structure, which in turn makes it particularly inexpensive to manufacture, but also has improved versatility in terms of the variations in light patterns that can be produced.

[0047] The light-emitting device may also include a base for connecting the light-emitting device to a lamp base and / or a lamp socket.

[0048] The present invention also relates to luminaires that include a light-emitting device according to the present invention. Such luminaires may be, for example, light bulbs, incandescent bulbs, or filament lamps.

[0049] It should be noted that the present invention relates to all possible combinations of the features described in the claims. Attached Figure Description

[0050] This and other aspects of the invention will now be described in more detail with reference to the accompanying drawings, which illustrate multiple embodiments of the invention.

[0051] Figure 1 A cross-sectional view of a light bulb having a light-emitting device according to the present invention is shown.

[0052] Figure 2A-2C A very schematic cross-sectional view of three embodiments of the light-emitting device according to the present invention is shown, and the positions of the LED and LD light sources of the light-emitting device are illustrated.

[0053] Figure 3 A cross-sectional view of an embodiment of a light-emitting device including a reflector according to the present invention is shown, with the LED omitted for simplicity.

[0054] Figure 4 A cross-sectional view of an embodiment of a light-emitting device including multiple reflectors according to the present invention is shown, with LEDs omitted for simplicity.

[0055] Figure 5 A cross-sectional view of an embodiment of a light-emitting device according to the present invention is shown, the light-emitting device comprising a section of elements of a non-scattering, low-scattering volumetric material, with LEDs omitted for simplicity.

[0056] Figure 6 A cross-sectional view of an embodiment of a light-emitting device according to the present invention is shown, the light-emitting device including a cover covering a portion of a low-scattering material, with LEDs omitted for simplicity.

[0057] Figure 7 A cross-sectional view of an embodiment of a light-emitting device according to the present invention is shown, wherein a TIR in a low-volume scattering material is used instead of a reflector, and an LED is omitted for simplicity.

[0058] Figure 8 A and Figure 8 B illustrates a transverse ( ) of an embodiment of a light-emitting device according to the present invention. Figure 8 A) and longitudinal ( Figure 8 B) Cross-sectional view of the light-emitting device, which includes elements in the form of light guides with low volume scattering material; LEDs are omitted for simplicity.

[0059] Figure 9-20 Different graphs of the intensity of light emitted by the light-emitting device according to the invention as a function of time are shown, and various operating modes of the light-emitting device according to the invention are illustrated.

[0060] As shown in the figures, the sizes of layers and regions have been exaggerated for illustrative purposes, and these sizes are thus provided to illustrate the general structure of embodiments of the invention. Similar reference numerals always denote similar elements. Detailed Implementation

[0061] The invention will now be described more fully below with reference to the accompanying drawings, in which presently preferred embodiments of the invention are illustrated. However, the invention may be embodied in many different forms and should not be construed as limited to the embodiments set forth herein; rather, these embodiments are provided for thoroughness and completeness and to fully convey the scope of the invention to those skilled in the art.

[0062] refer to Figures 1 to 3 The light-emitting device 1 according to the present invention is shown in cross-section. Figure 1 A light-emitting device 1 used in a bulb 10 is shown. Figure 2A , Figure 2B , Figure 2C and Figure 3 Four different illustrative versions of the light-emitting device 1 are shown in cross-section.

[0063] For details, please refer to the following: Figures 2A to 3 The light-emitting device 1 generally and independently of the embodiment includes: an element 2 comprising a volumetric low-scattering material; at least one red laser diode (LD) 3 configured to emit a red laser 31 in operation; a collimating lens 4 arranged and configured to collimate the red laser 31; and at least one LED 5, 51, 52, 53 configured to emit LED light in operation.

[0064] Element 2 includes opposing first and second light-incident surfaces 21 and 22, and a circumferential surface 23 extending between and connecting the first and second light-incident surfaces 21 and 22. The circumferential surface 23 acts as a light-out coupling surface, through which light is coupled out of element 2 by scattering. Element 2 is made of a low-scattering material. Element 2 is configured to make the path 6 of the laser 31 visible. Element 2 can also be configured to make the path of the LED light visible. Element 2 may, but does not necessarily, be rod-shaped. Element 2 may, but does not necessarily, be filament-shaped.

[0065] The low-scattering material of element 2 can be a solid material. The low-scattering material can include particles 24 with a size smaller than 1 / 10 of the wavelength of the red laser 31. Figure 3 Alternatively or additionally, the volumetric low-scattering material may include particles 24 with a size larger than the wavelength of the red laser 31. Particles 24 may be scattering particles. In yet another alternative, particles 24 may be omitted. The volumetric low-scattering material may be a plastic, such as polycarbonate or PMMA. The volumetric low-scattering material may also be a foam with light-redirecting properties.

[0066] The red LD 3 is configured to emit a red laser 31 during operation. The red LD 3 is disposed at or near one of the first and second optical coupling surfaces 21 and 22. As shown, the LD 3 is disposed at the optical coupling surface 21 such that the red laser 31 is coupled into the element 2 through the optical coupling surface 21. Alternatively, the LD 3 may be disposed at the optical coupling surface 22.

[0067] Collimator 4 is disposed at one of the first optical incident surface and the second optical incident surfaces 21 and 22, as shown in the figure, with optical incident surface 21 located between optical incident surface 21 and red LD 3. Collimator 4 may be, for example, a collimating lens 4.

[0068] At least one LED 5, 51, 52, 53 is disposed at, adjacent to, or on one of the first and second light-incident surfaces 21 and 22. Figure 2A-2C As shown, LD 3 is arranged at light-injection surface 21, and at least one LED 5, 51, 52, 53 is arranged at light-injection surface 22, such that LED light is coupled into element 2 through light-injection surface 22. In other words, at least one LED 5, 51, 52, 53 and red LD 3 can be arranged at mutually opposite light-injection surfaces 21 and 22 of element 2. If LD 3 is arranged at light-injection surface 22, then LED 5, 51, 52, 53 can therefore be arranged at light-injection surface 21. Alternatively, LD 3 and at least one LED 5, 51, 52, 53 can be arranged at the same light-injection surface 21 or 22.

[0069] At least one LED 5 can emit white light, see Figure 2A At least one LED 51, 52 can also emit blue and yellow light, see [link / reference] Figure 2B At least one LED 51, 52, 53 can also emit red, green, and blue light; see [link to relevant documentation]. Figure 2C .

[0070] For details, please refer to the following: Figure 3 The light-emitting device 1 also includes a reflector 7. The reflector 7 is arranged at the light-introduction surface 22 of the element 2 opposite to the light-introduction surface 21. A red LD 3 is arranged at the light-introduction surface 21 so as to reflect the red laser 31 emitted by the red LD 3 back into the element 2 in a rearward direction toward the red LD 3. As a result, the red LD light is amplified and its visibility is increased.

[0071] Figure 4A light-emitting device 100 according to another embodiment of the present invention is shown. The light-emitting device 100 and... Figure 3 The only difference between the light-emitting devices is the following feature. The light-emitting device 100 includes a plurality of reflectors 71, 72. The reflectors 71, 72 and the red laser diode 3 are positioned relative to each other in such a way that the red laser reflected by at least one reflector (e.g., reflector 71) propagates in a direction D2, which is different from the direction D1 of propagation of the red laser 31 incident on reflector 71. It can be seen that some of the reflectors (e.g., reflector 72) can be arranged at the first light-incident surface 21 (i.e., on the same side as the red LD 3), but offset from the red LD 3. For example, the red laser incident on reflectors 71, 72 can be reflected by reflectors 71, 72 at a reflection angle ranging from 10 degrees to 60 degrees.

[0072] The result is that the red laser 31 incident on reflector 71 propagates along the first path 61, while the red laser reflected by reflector 71 propagates along a different second path 62. Furthermore, the red laser incident on reflector 72 propagates along the second path 62, while the red laser reflected by reflector 72 propagates along a different third path. This results in an appearance corresponding to more than one filament. Figure 4 As shown, eight reflectors 71, 72 are provided. In other embodiments, an additional number of reflectors 71, 72 may be provided, such as from two to seven or more than eight reflectors.

[0073] like Figure 4 As shown, different paths 61 and 62 are obtained by placing the red LD 3 such that the laser 31 propagates to the light-incident surface 21 at an angle different from the right angle P perpendicular to the light-incident surface 21, particularly an acute angle β, and by placing the reflector 71 such that its reflective surface extends parallel to the second light-incident surface 22. Alternatively, the red LD 3 can be placed such that the laser 31 propagates at an angle perpendicular to the light-incident surface 21, and the reflector 71 can be placed such that its reflective surface extends at an angle to the second light-incident surface 22, particularly at an acute angle to the second light-incident surface 22.

[0074] Figure 5 A light-emitting device 101 according to another embodiment of the present invention is shown. The light-emitting device 101 and... Figure 3 and Figure 4 The only difference between the light-emitting devices is the following feature. The light-emitting device 101 includes only one reflector 7, which is referenced above by the reflector 71 and... Figure 4The arrangement is as described. The volumetric low-scattering material of element 2 includes a segment 25 suitable for not scattering light. The volumetric low-scattering material of element 2 may also include more than one segment 25 suitable for not scattering light. The segment 25 may be an end segment of element 2 adjacent to one or both of the light incident surfaces 21 and 22.

[0075] Figure 6 A light-emitting device 102 according to another embodiment of the present invention is shown. The light-emitting device 102 and... Figures 3 to 5 The only difference between the light-emitting devices is the following feature. Element 2 includes at least one part covered by a cover 26 or a coating.

[0076] Figure 7 A light-emitting device 103 according to another embodiment of the present invention is shown. The light-emitting device 103 and... Figures 3 to 6 The only difference between the light-emitting devices is the following feature. The red LD 3 is arranged at an angle relative to the light-injection coupling surface 21 such that the laser 31 coupled into the element 2 is reflected within the element 2 by total internal reflection (TIR) ​​at the circumferential surface 23 of the element 2. Thus, the use of reflector 7 can be avoided, and line patterns of paths 61, 62 can be produced.

[0077] Figure 8 A light-emitting device 104 according to another embodiment of the present invention is shown. The light-emitting device 104 has a cross-sectional area of ​​( ) Figure 8 A) and longitudinal section ( Figure 8 B) shows the light-emitting device 104 and Figures 3 to 7 The difference between this light-emitting device and others lies only in the following features. In this embodiment, element 2 is provided in the form of a light guide comprising a low-scattering material. The light guide is rod-shaped and includes a circular transverse cross-section (see...). Figure 8 A). Thus, the red laser 31 from the red LD 3 can be coupled into the optical guide in such a way that it propagates through the optical guide via total internal reflection (TIR) ​​at the circumferential surface 23. This allows the path segments 61-64 (see...) to be obtained. Figure 8 A) forms the spiral path 6 (see Figure 8 B).

[0078] Refer again Figure 1 The light-emitting device (or in fact a combination of such embodiments) according to any of the embodiments described herein can be used in luminaires such as light bulbs. Figure 1 The illustrated luminaire includes two light-emitting devices 1 according to the invention by way of non-limiting example. The luminaire may also include one, three or more light-emitting devices according to the invention.

[0079] The luminaire includes a luminaire socket 12 and luminaire bases 13 and 15, which are used to mechanically and / or electrically connect the light-emitting device 1 to the luminaire socket 12. The luminaire socket 12 may also include a terminal 14 for electrical connection to an external power source.

[0080] Therefore, the light-emitting device may also include bases 8 and 16 for connecting the light-emitting device to lamp bases 13 and 15 and thereby to lamp socket 12. Lamp socket 12 supplies power to LEDs 51, 52, 53 and red LD 3 of the light-emitting device 1 through lamp bases 13 and 15, respectively.

[0081] The light-emitting device may also include a light-transmitting envelope 9 that at least partially surrounds a low-volume scattering material of the element 2.

[0082] like Figure 1 As shown, the lamp bases 13 and 15, and especially the lamp base portion, can also serve as brackets or supports for supporting the light-emitting device 1.

[0083] In another embodiment, it is also feasible to omit the lamp bases 13 and 15. In this case, at least one of the bases 8 and 16 of the light-emitting device 1 is adapted to be directly connected to the lamp socket 12.

[0084] The illuminator may also include a casing structure or a bulb 11 that partially or completely surrounds the light-emitting device. In the illustrated embodiment, the casing or bulb 11 is arranged at a distance from the light-emitting device.

[0085] Now go to Figure 9-20 Different graphs showing the intensity of light emitted by the light-emitting device according to the present invention as a function of time are illustrated. Figure 9-20 The graph illustrates various operating modes of the light-emitting device according to the invention over time in terms of controlling the intensity of light emitted by LD 3 and at least one LED 5, 51, 52, 53, respectively.

[0086] exist Figure 9 In the operating mode shown, the intensity of the LED light remains constant, while the intensity of the laser 31 changes over time. This creates a combustion light effect.

[0087] exist Figure 10 In the operating mode shown, the intensity of the LED light changes over time, while the intensity of the laser 31 remains constant. This also achieves a combustion light effect.

[0088] exist Figure 11 In the operating mode shown, the intensity of both the LED light and the laser 31 changes over time, but in different ways. This allows for a more random variation in the optical effect.

[0089] exist Figure 12 In the operating mode shown, the intensity of both the LED light and the laser 31 changes over time and now follows the same pattern.

[0090] exist Figure 13 In the operating mode shown, the intensity of both the LED light and the laser 31 changes over time, and now follows the same but opposite patterns.

[0091] exist Figure 14 In the operating modes shown, at low intensity, only the LD is turned on and emits light at an increased intensity, while at high intensity, only the LED is turned on and emits light at an increased intensity.

[0092] exist Figure 15 In the operating mode shown, at low intensity, only the LD is turned on and emits light with increasing intensity, while at high intensity, the LD is turned on and emits light with constant intensity, and the LED is turned on and emits light with increasing intensity.

[0093] exist Figure 16 In the operating mode shown, at low intensity, only the LD is turned on and emits light at an increased intensity, while at high intensity, the LD is turned on and emits light at a decreased intensity, and the LED is turned on and emits light at an increased intensity.

[0094] exist Figure 17 In the operating modes shown, at low intensity, only the LD is turned on and emits light at an increased intensity, while at high intensity, both the LD and the LED are turned on and emit light at an increased intensity.

[0095] exist Figure 18 In the operating mode shown, the light-emitting device includes an RGB LED package. At low intensity, only the LD and the green and blue LEDs are turned on and emit light at an increasing intensity, while at high intensity, the LD is turned on and emits light at a constant intensity, and the entire RGB LED package is turned on and emits light at an increasing intensity.

[0096] exist Figure 19 In the operating mode shown, the light-emitting device includes an RGB LED package. The green and blue LEDs emit light at a constant intensity, while the red LEDs and LDs emit light at varying intensities.

[0097] Finally, Figure 20 In the operating mode shown, the light-emitting device includes an RGB LED package. The green and blue LEDs emit light at a constant intensity, while the red LEDs and LD emit light at varying intensities that are opposite to each other.

[0098] Those skilled in the art will recognize that the present invention is by no means limited to the preferred embodiments described above. Rather, many modifications and variations are possible within the scope of the appended claims.

[0099] Additionally, from a study of the drawings, disclosure, and appended claims, those skilled in the art can understand and implement variations of the disclosed embodiments when practicing the claimed invention. In the claims, the word "comprising" does not exclude other elements or steps, and the indefinite articles "a" or "an" do not exclude a plurality. The mere fact that certain measures are recited in mutually different dependent claims does not imply that combinations of these measures cannot be advantageously used.

Claims

1. A light emitting device (1), comprising: - an element (2) comprising a bulk low scattering material, the element comprising opposite first and second light incoupling surfaces (21, 22) and a circumferential surface (23) extending between and connecting the first and second light incoupling surfaces, - at least one red laser diode (3) configured to emit red laser light (31) in operation and arranged at one of the first and second light incoupling surfaces such that the red laser light is coupled into the element through the one of the first and second light incoupling surfaces, - a collimator (4) arranged and configured to collimate the red laser light (31) into collimated red laser light (31a), - at least one LED (5, 51, 52, 53) configured to emit LED light in operation, the at least one LED being arranged at one of the first and second light incoupling surfaces such that the LED light is coupled into the element through the one of the first and second light incoupling surfaces, and - the bulk low scattering material of the element (2) configured to make the path of the laser light visible.

2. The light emitting device according to claim 1, wherein the bulk low scattering material is a solid material comprising particles (24) having a size smaller than 1 / 10 of the wavelength of the red laser light.

3. The light emitting device according to claim 1, wherein the bulk low scattering material is a solid material comprising particles (24) having a size larger than the wavelength of the red laser light.

4. The light emitting device according to claim 1, wherein the collimator (4) is configured to provide the collimated red laser light with a collimation of less than 1 degree FWHM.

5. The light emitting device according to claim 4, wherein the element (2) is configured such that the collimated red laser light is visible in the element over at least a length L, wherein L is at least 5 cm.

6. The light emitting device according to any one of claims 1-5, and further comprising at least one reflector (7, 71) arranged at the light incoupling surface of the element opposite the light incoupling surface at which the red laser diode (3) is arranged, so as to reflect the red laser light emitted by the red laser diode back into the element.

7. The light emitting device according to claim 6, wherein the at least one reflector (7, 71) and the red laser diode (3) are positioned relative to each other in such a way that the red laser light reflected by the at least one reflector propagates in a direction (D2) different from a direction opposite to a direction (D1) of propagation of the red laser light incident on the at least one reflector.

8. The light emitting device according to claim 6, and further comprising at least one reflector (72) arranged at the same light incoupling surface as the red laser diode (3) and offset from the red laser diode (3).

9. The light emitting device according to any one of claims 1-5 and 7-8, wherein the element comprises at least one section (25) adapted to not scatter light.

10. The light emitting device according to any one of claims 1-5 and 7-8, wherein the element comprises at least one section covered by a cap (26) or a coating.

11. The light emitting device according to any one of claims 1-5 and 7-8, wherein the element is provided in the form of a light guide (20) in which LED light emitted by the at least one light emitting device can be reflected multiple times by total internal reflection, the light guide (20) comprising a low scattering material.

12. The light emitting device according to any one of claims 1-5 and 7-8, wherein the at least one LED (5, 51, 52, 53) is configured to emit, in operation, any one of the following: white LED light, blue and green / yellow LED light, and red, green and blue LED light.

13. The light emitting device according to any one of claims 1-5 and 7-8, and further comprising any one or more of: a base (8, 16) for connecting the light emitting device to one or more of a luminaire base (13, 15) and a luminaire socket (12), and an at least partly light transmissive envelope (9) at least partly enclosing the element (2) comprising a volume of low scattering material.

14. The light emitting device according to any one of claims 1-5 and 7-8, wherein the element (2) comprising a volume of low scattering material is a rod-like element or a filament-like element.

15. A luminaire comprising a light emitting device (1) according to any one of claims 1-14.

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